SAN DIEGO (CBS 8) - A San Diego breeding center is celebrating the birth of four Mexican gray wolves.

The Mexican gray wolf is considered one of the rarest land mammals in the world. Starting in 1976, the animals were listed on the endangered species list.

In April, four pups were born at the California Wolf Center, and may be released into the wild.

"Every time pups are born they're valuable to the program, but these pups in particular have rare genes to contribute to the population," Erin Hunt of the California Wolf Center said.

The wolves are being released into the wild in Arizona and New Mexico, with about 50 living in the wild today.

The California Wolf Center, located in the back country town of Julian in San Diego County, is the third-largest breeding and hosting facility for Mexican gray wolves in the United States.